Oxygen generator and method for starting or accelerating the oxygen production of an oxygen generating composition

ABSTRACT

An oxygen generator has a composition for generating oxygen and a basic compound. The composition for generating oxygen includes an oxygen source, an ionic liquid, a metal salt, and an optional basic compound. The oxygen source is a peroxide compound, the ionic liquid is in the liquid state at least in a temperature range from −10° C. to +50° C., the metal salt has one single metal or two or more different metals, and an organic and/or an inorganic anion. There is also described a method for starting or accelerating the oxygen production of an oxygen generating composition, and a device for generating oxygen in a controlled manner.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation, under 35 U.S.C. § 120, of copendingInternational Patent Application PCT/EP2019/070423, filed Jul. 30, 2019,which designated the United States; this application also claims thepriority, under 35 U.S.C. § 119, of European Patent Application EP18186432.3, filed Jul. 30, 2018; the prior applications are herewithincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to oxygen generators, compositions,methods and devices for generating oxygen in a controlled manner.

Humans cannot exist without oxygen. In many environments, however,oxygen supply is insufficient or there is a risk of emergency situationsinvolving a shortage of oxygen, for example in SAR (search and rescue)applications, in submarines, in mines, in space capsules, and also inairplanes. Air pressure decreases with increasing flight altitude, andat cruising altitudes of many aircrafts, in particular long-rangeaircrafts, sufficient oxygen for human beings is no longer available.Therefore, the aircraft cabins are pressurized in order to ensuresufficient oxygen supply. In the case of a sudden de-pressurization ofan aircraft cabin, oxygen masks must be available, which supply oxygento crew and passengers until the aircraft reaches a flight level wheresufficient oxygen is available.

The oxygen which is provided by these emergency systems is typicallyproduced by so-called “chlorate candles” or “oxygen candles”. Thesechemical oxygen generators contain chlorates or perchlorates as anoxygen source, as well as various additives such as fuels, catalysts,binders and moderators. Chlorate candles are often in the form ofcylindrical rods, i.e. they have a shape similar to candles. Chloratecandles are disclosed, for example, in international publication WO97/43210.

Known chlorate candles require high temperatures at which the oxygenproduction takes place. Namely, in chlorate candles the decompositionreaction requires a temperature of about 350° C. for initiation, and theoxygen is released at temperatures between 450° C. and 700° C.Therefore, effective heat insulation of chlorate candles is required,resulting in a weight and size penalty. Furthermore, decomposition ofchlorates and perchlorates tends to produce toxic side products, inparticular chlorine, which must be removed from the oxygen stream, thusadditionally adding size and weight. Furthermore, there is a risk ofsystem failure. In chlorate candles the reaction zone is normallyliquid, i.e. there is a liquid zone traveling through the candle,starting at the point of ignition. The liquid zone within the otherwisesolid candle considerably destabilizes the candle such that mechanicalshocks or even slight vibrations may result in the separation of thecandle portions, thus interrupting the heat transfer and discontinuingthe chlorate or perchlorate decomposition. In such a case, oxygenproduction may be interrupted, although oxygen is still vitally needed.

A different type of chemical oxygen generators uses peroxides as oxygensources, for example sodium percarbonate, sodium perborate, or an ureaadduct of hydrogen peroxide. Decomposition of the peroxides yieldsoxygen, and the decomposition reaction can be started by contacting theperoxide compounds with an appropriate enzyme or transition metalcatalyst. Chemical oxygen generators of this type are disclosed in U.S.Pat. No. 2,035,896, international publication WO 86/02063, Japanesepublication JPS 61227903, and German publication DE 196 02 149.

Many known peroxide-based oxygen generators use water for providingcontact between the peroxides and the catalysts. Unfortunately, waterfreezes at 0° C. and, therefore, no oxygen can be produced below 0° C.,while some emergency systems must be operational below 0° C. Also, thedecomposition of peroxides in aqueous solutions may result in vehementeffervescing of the reaction mixture. As a consequence, an oxygengenerating device containing a peroxide-based oxygen generatingcomposition must have a complicated structure.

A new concept is disclosed in our commonly assigned European patentapplications EP 3 323 471 A1, EP 3 323 782 A1 and EP 3 323 783 A1. Thosedocuments disclose devices, compositions and methods for generatingoxygen from peroxides in ionic liquids. The compositions comprise atleast one oxygen source, at least one ionic liquid, and at least onemetal oxide compound, wherein the oxygen source comprises a peroxidecompound, the ionic liquid is in the liquid state at least in atemperature range from −10° C. to +50° C., and the metal oxide compoundis an oxide of one single metal or of two or more different metals, themetal(s) being selected from the metals of groups 2 to 14 of theperiodic table of the elements.

The use of ionic liquids provides for distinct advantages. Ionic liquidsare environmentally friendly compounds. They are liquid over a broadtemperature range and exhibit a low to non-existing vapor pressure.Moreover, these liquids are non-flammable and are even used as flameretardants which makes them highly attractive for the use in anairplane. Many of their other properties can be varied by changing theirmolecular structures. Their high heat capacity enables them to dissipatethe reaction heat from the decomposition of peroxides to oxygen.

The compositions disclosed in the prior publications EP 3 323 471 A1, EP3 323 782 A1 and EP 3 323 783 A1 produce breathable oxygen reliably andcontinuously in a wide temperature range, also including subfreezingtemperatures. The oxygen produced is at a low temperature, such as below150° C. or even lower. It is typically free from toxic or otherwisenoxious components such as chlorine or carbon monoxide. The compositionsare capable to produce oxygen over an extended period of time and with asignificant flow rate, and promptly upon demand.

However, all oxygen generating compositions described above have incommon that they produce oxygen at a flow rate inherent to theparticular system, and once the decomposition reaction of the oxygensource has started, it cannot be stopped until all of the oxygen sourcehas been decomposed. Thus, there may be situations, where oxygen isproduced although it is not needed or not needed in the amount produced,while later, when oxygen or more oxygen may be needed again, there is nolonger any oxygen or no longer enough oxygen available. Furthermore,there may be situations, where not enough oxygen per time unit isproduced although it is needed, e.g. because the constitution of aspecific person requires a higher oxygen production rate than an averageperson. Such situations occur frequently in SAR applications, in mining,submarine and space flight applications. If in a conventional oxygengenerator the oxygen production is interrupted, intentionally orunintentionally (as may happen in chlorate oxygen candles), there is nopossibility to restart the oxygen production. Furthermore, under phasesof particularly severe physical strain of a user, there is temporarilymore oxygen required, but prior art oxygen generators cannot provide anincreased oxygen supply for a desired period of time.

BRIEF SUMMARY OF THE INVENTION

It would be beneficial to provide a solution to at least some of theproblems of the prior art outlined above and to provide an oxygengenerator allowing to modify the oxygen production rate, i.e., toincrease or decrease the oxygen flow rate. It would be also beneficialto provide an oxygen generator which allows to stop the oxygenproduction when no oxygen is needed, and to restart the oxygenproduction whenever oxygen is needed. It would be particularlybeneficial, when stoppage and restart of the oxygen production could beperformed several times.

In addition, it would be beneficial if this oxygen generator would becapable of producing breathable oxygen reliably and continuously in awide temperature range, and preferably including subfreezingtemperatures. The oxygen produced should be at a low temperature, suchas below 150° C. or even lower. Desirably, the oxygen should be freefrom toxic or otherwise noxious components such as chlorine or carbonmonoxide. It would be also beneficial if the oxygen generator would becapable to produce oxygen over an extended period of time and with asignificant flow rate, and preferably promptly upon demand.

With the above and other objects in view there is provided, inaccordance with the invention, an oxygen generator, comprising:

a composition for generating oxygen including an oxygen source, an ionicliquid, and a metal salt, and

a basic compound for starting or accelerating oxygen production;

the oxygen source comprising a peroxide compound;

the ionic liquid being in the liquid state at least in a temperaturerange from −10° C. to +50° C.; and

the metal salt having one single metal or two or more different metals,and an organic and/or an inorganic anion.

In other words, exemplary embodiments of the invention include an oxygengenerator comprising a composition for generating oxygen comprising anoxygen source, an ionic liquid and a metal salt, and a basic compoundfor starting or accelerating oxygen production, wherein the oxygensource comprises a peroxide compound, the ionic liquid is in the liquidstate at least in a temperature range from −10° C. to +50° C., the metalsalt comprises one single metal or two or more different metals, and anorganic and/or an inorganic anion. Metal(s) of the salt mean(s) here andin the following metal ion(s). The metal salt as such is not able tocatalyze decomposition of the peroxide and therewith oxygen production.For starting oxygen production, the metal(s) of the metal salt has/haveto be oxidized. This occurs automatically when the basic compound isadded. Presumably, the peroxide serves as oxidizing agent for themetal(s). The metal(s) of the metal salt of the present invention may beselected from the metals of groups 2 to 14 of the periodic table of theelements. The periodic table has 18 groups (see: Pure and AppliedChemistry, vol. 60, 3, pages 431-436).

Starting oxygen production may be a first starting of oxygen productionfrom an oxygen generating composition or a further starting, i.e., arestart, after an interruption of oxygen generation by addition anacidic compound.

Further exemplary embodiments of the invention include a composition forgenerating oxygen comprising an oxygen source, an ionic liquid, a metalsalt, and a basic compound, or, if the ionic liquid is a basic ionicliquid or the oxygen source is basic, comprising an oxygen source, anionic liquid and a metal salt, wherein the oxygen source comprises aperoxide compound, the ionic liquid is in the liquid state at least in atemperature range from −10° C. to +50° C. and the metal salt comprisesone single metal or two or more different metals, and an organic and/oran inorganic anion.

Further exemplary embodiments of the invention include a method forstarting or accelerating oxygen production of an oxygen generatingcomposition. In the sense of the invention an oxygen generatingcomposition is a composition already generating oxygen but also acomposition for generating oxygen in which oxygen generation still hasto be started. The method comprises providing an oxygen source,providing an ionic liquid, providing a metal salt, contacting the oxygensource, the ionic liquid and the metal salt, and starting oraccelerating the oxygen production by adding a basic compound to theoxygen source, the ionic liquid and/or the metal salt, wherein theoxygen source comprises a peroxide compound, the ionic liquid is in theliquid state at least in the temperature range from −10° C. to +50° C.and the metal salt comprises one single metal or two or more differentmetals and an organic and/or an inorganic anion. Addition of the basiccompound to the oxygen source, the ionic liquid and/or the metal saltmay occur before, during or after contacting of the oxygen source, theionic liquid and the metal salt. If it occurs before, it is sufficientto add it to one or two out of the oxygen source, the ionic liquid andthe metal salt.

Further exemplary embodiments of the invention include a device forgenerating oxygen in a controlled manner, the device comprising areaction chamber housing a composition for generating oxygen, thecomposition comprising a combination of constituents consisting of anoxygen source, an ionic liquid, and a metal salt, at least one dosingdevice housing a basic compound and, optionally, at least one dosingdevice housing an acidic compound, the dosing device(s) being adapted tointroduce the basic compound and, optionally, the acidic compound intothe reaction chamber, means for maintaining at least one of the oxygensource, the ionic liquid and the metal salt physically separated fromthe remaining constituents, means for establishing physical contact ofthe oxygen source, the ionic liquid and the metal salt, and means forallowing oxygen to exit the reaction chamber, or, in particular if theionic liquid is an acidic compound or contains an acidic compound, areaction chamber housing a composition for generating oxygen, thecomposition comprising a combination of constituents consisting of anoxygen source, an ionic liquid, and a metal salt, means for allowingoxygen to exit the reaction chamber, at least one dosing device housinga basic compound and, optionally, at least one dosing device housing anacidic compound, the dosing device(s) being adapted to introduce thebasic compound and, optionally, the acidic compound into the reactionchamber, wherein the metal salt comprises a single metal or two or moredifferent metals, and an organic and/or an inorganic anion, the oxygensource comprises a peroxide compound, and the ionic liquid is in theliquid state at least in the temperature range from −10° C. to +50° C.In said device for generating oxygen the oxygen production rate isadjusted by adding the basic compound or, optionally, the acidiccompound to the composition for generating oxygen. If oxygen productionshall be increased, started or restarted this occurs by the addition ofthe basic compound and if it shall be decreased or stopped this occursby the addition of the acidic compound. Since oxygen generation startsonly after oxidation of the metal of the metal salt and this oxidationtakes only place under basic conditions, it may be not required toprovide means for maintaining at least one of the oxygen source, theionic liquid and the metal salt physically separated from the remainingconstituents and means for establishing physical contact of the oxygensource, the ionic liquid and the metal salt if conditions are not basic.However, the composition of the oxygen source, the ionic liquid and themetal salt may be basic as such, e.g. if the ionic liquid or the oxygensource is basic.

Each of the dosing devices may be adapted to introduce the basiccompound or the acidic compound by providing a feed line leading from areservoir housing the basic compound or the acidic compound to thereaction chamber. The feed line may be equipped with a valve the openingof which allows the basic compound or the acidic compound to flow, e.g.due to gravity, into the reaction chamber. When closed or if the valveis a one-way valve the valve may also prevent flow of fluid or oxygenfrom the reaction chamber into the feed line or even in the reservoir.The reservoir may be equipped with a piston or slide bar for pressingthe basic compound or the acidic compound via the feed line into thereaction chamber. The counterpressure provided by the piston or slidebar can prevent that fluid or generated oxygen passes the feed line fromthe reaction chamber into the reservoir such that a valve is notabsolutely required, in particular when the feed line has a smalldiameter.

Technical implementations of the inventive concept as claimed hereininclude a composition for generating oxygen, an oxygen generatorcomprising a composition for generating oxygen, a method for generatingoxygen, a method for starting or accelerating the oxygen production ofthe oxygen generator, and a device for generating oxygen in a controlledmanner.

In the method of this invention, oxygen is produced from the compositionfor generating oxygen, and the oxygen production is accelerated orstarted by adding a basic compound.

As can be easily understood, the constituents of the composition forgenerating oxygen are corresponding, irrespective of which technicalimplementation of the invention is contemplated. Therefore, anydisclosure provided for a particular implementation, such ascomposition, oxygen generator, method or device is analogouslyapplicable to the other implementations of this invention.

A composition for generating oxygen, an oxygen generator (including acomposition for generating oxygen and an acidic compound and/or a basiccompound), a method for starting or accelerating the oxygen production,and a device for generating oxygen in the sense of this invention is acomposition, generator, method or device for generating gaseous, inparticular breathable, oxygen in particular in an amount and at anoxygen production rate sufficient to maintain breathing of a human beingfor a limited time. Any composition, generator, method or deviceyielding oxygen as a side reaction product, in particular in an amountand at an oxygen production rate not sufficient to maintain breathing ofa human being for a limited time, does not constitute a composition, agenerator, a method or device in the sense of this invention.

The oxygen generator, the composition, the method for accelerating orstarting the oxygen production and the device for generating oxygen in acontrolled manner enable acceleration or starting of oxygen production.This enables to provide a composition containing all constituents otherthan the basic compound and to start oxygen production just by addingthe basic compound. It is also possible to restart oxygen productionafter it had been stopped by addition of an acidic compound.Furthermore, accelerating oxygen production allows adaption of theoxygen production rate to its real need such that at least the requiredamount of oxygen per time unit but not more oxygen per time unit thanrequired is produced. Due to the possibility to adapt oxygen productionto the need of oxygen the oxygen generator, the composition, the methodand the device according to the invention allow for a longer provisionof sufficient oxygen for a human being and therewith a longer survivalof the human being in an emergency situation than with oxygengenerators, compositions, methods and devices providing oxygen in anuncontrolled manner.

The invention enables a precise adjustment of the oxygen productionrate. If oxygen has to be provided for a defined time, the oxygengenerator or the device can contain a smaller amount of the oxygengenerating composition than oxygen generators and devices providingoxygen in an uncontrolled manner. Thus, the weight of such an oxygengenerator or device comprising the oxygen generating composition can belower than the weight of an oxygen generator or device known in the art.This is important, e.g. if the oxygen generator or the device is used asan emergency system in an airplane.

The compositions for generating oxygen according to further exemplaryembodiments of the invention comprise at least the followingconstituents: a peroxide compound as an oxygen source, a metal salt as acatalyst triggering the oxygen release reaction, an ionic liquid as acarrier for providing contact between the oxygen source and thecatalyst, and for dissipating the heat generated during the peroxidedecomposition reaction and, if the ionic liquid is not a basic ionicliquid or the oxygen source is not basic, a basic compound for startingor accelerating oxygen production. In exemplary embodiments the metalsalt is soluble in the ionic liquid. The term “soluble” means thatessentially the complete amount of the metal salt of a particular oxygengenerating composition can be dissolved in the amount of ionic liquidused in this particular composition. The ratio of oxygen source:ionicliquid:metal salt can be varied, however, due to space constraints andalso for economical reasons it is advantageous to keep the amount ofionic liquid reasonably small. Therefore, for the purpose of thisinvention, “soluble” means a solubility of at least 10 nmol (nanomol)metal salt in 1 g ionic liquid. In further exemplary embodiments, themetal salt is only partially soluble or insoluble in the ionic liquid.Typically, the metal salt catalysts have at least some solubility, i.e.are partially soluble.

Peroxide compounds such as hydrogen peroxide adduct compounds, can bedecomposed in ionic liquids by contacting them with metal salts in asimilar manner as metal salts in aqueous solution, but without thedisadvantages of reactions catalyzed by metal salts in aqueoussolutions. Exemplary compositions of this invention do not contain anywater or at least only traces of water contained in the constituents ofthe composition. In particular, decomposition of peroxide compounds inionic liquids yields breathable oxygen at low temperatures, and withoutrequiring bulky thermal insulations for the oxygen generating device.

This can be attributed to the use of ionic liquids as a medium forproviding contact between the oxygen source and the catalyst.

Ionic liquids are salts in the liquid state. Therefore, any salt thatmelts without decomposing or vaporizing yields an ionic liquid.Sometimes, salts which are liquid below the boiling point of water areconsidered as ionic liquids. Technically interesting are in particularthose ionic liquids which are in the liquid state at relatively lowtemperatures such as at room temperature or even below room temperature.

An ionic compound is considered as an ionic liquid herein when it is inthe liquid state at least in a temperature range from −10° C. to +50° C.(at standard pressure of 10⁵ Pa). Exemplary ionic liquids are in theliquid state at least from −30° C. to +70° C., and further exemplaryionic liquids are in the liquid state in an even broader temperaturerange such as from −70° C. to +150° C. All temperatures referring to theliquid state of ionic liquid given herein particularly refer to theionic liquid at standard pressure of 10⁵ Pa.

The properties of ionic liquids can be modified and adapted to theparticular needs by varying the chemical structure. Typically, ionicliquids are thermally stable, have wide liquid regions, a high heatcapacity and nearly no vapor pressure. Most of them are incombustible.They can be even used as flame retardants. Reference is made to US2011/0073331 A1 disclosing ionic liquid flame retardants, and quotingliterature disclosing preparation methods (paragraph 0127).

As indicated above, the ionic liquids used in the present inventionshould be in the liquid state at a low temperature, such as down to −10°C., or down to −30° C. or even below. Such ionic liquids are saltsconsisting of organic cations and organic or inorganic anions, and bothcations and anions are bulky. In exemplary embodiments, they are bulkyand asymmetric. As a general rule, the melting temperature decreaseswith increasing bulkiness and decreasing symmetry of cations and anions.Combinations of highly bulky and asymmetric cations and anions may notfreeze down to temperatures as low as −120° C. Many ionic liquids areavailable which are liquid at −70° C. and above.

Suitable cations are, for example, imidazolium, pyrrolidinium, ammonium,pyridinium, pyrazolium, piperidinium, phosphonium, and sulfoniumcations. The cations may or may not have substituents. Particularly, thecations may have one or more substituents, for example alkyl side chainssuch as methyl, ethyl or butyl side chains. The substitution may besymmetric or asymmetric.

Suitable anions include, for example, dimethylphosphate, methylsulfate,ethylsulfate, trifluoromethylsulfonate,bis(trisfluoromethylsulfonyl)imide, chloride, bromide, iodide,tetrafluoroborate, hexafluorophosphate, acetate, and but-3-enoate. Inthe case of “small” anions such as chloride, bromide, and iodide,particularly bulky cations can be selected, in order to provide for thedesired low temperature liquidity.

Some exemplary ionic liquids are

-   -   1-butyl-3-methylimidazoliumdimethylphosphate ([BMIM][PO₄Me₂]),    -   1,3-dimethylimidazoliumdimethylphosphate ([MMIM][PO₄Me₂]),    -   1-butyl-3-methylimidazoliumacetate ([BMIM][OAc]),    -   1-ethyl-3-methylimidazoliumethylsulfate ([EMIM][EtSO₄]),    -   tetraethylammonium but-3-enoate ([NEt₄][but-3-enoat]),    -   1,3-dimethylimidazoliummethylsulfate ([MMIM][MeSO₄]),    -   1-butyl-3-methylimidazoliummethylsulfate ([BMIM][MeSO₄]),    -   1,1-butylmethylpyrrolidiniumbis(trifluoromethylsulfonyl)imide        ([BMPyrr][TFSI]),    -   butyltrimethylammoniumbis(trifluoromethylsulfonyl)imide        ([Me₃BuN][TFSI]),    -   1-butyl-3-methylimidazoliumtrifluoromethanesulfonate        ([BMIM][OTf]),    -   1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]),    -   tetrabutylammonium arginine ([TBA][Arg]),    -   trimethylammonium propanesulfonic acid hydrogen sulfate        ([TMPSA][HSO₄]),    -   1-(4-sulfobutyl)-3-methylimidazolium hydrogen sulfate        ([SBMIM][HSO₄]),    -   diethylmethylammonium methanesulfonate ([NEt₂MeH][MeSO₃]), and    -   1-ethyl-3-methylimidazolium hydrogen sulfate ([EMIM][HSO₄]).

[NEt₄][but-3-enoate], [EMIM][OAc] and [TBA][Arg] are basic ionicliquids, and [TMPSA][HSO₄], [SBMIM][HSO₄], [NEt₂MeH][MeSO₃] and[EMIM][HSO₄] are acidic ionic liquids.

Further ionic liquids can be found in “Neue Anwendungen für ionischeFlüssigkeiten in der Technik and Medizintechnik” (New Applications forIonic Liquids in Technology and Medical Technology), Dissertation by F.Stein, University of Rostock, Germany, 2014, at page 43.

The ionic liquids usable herein are, however, not particularly limited.It is only required that they are liquid and stable (i.e. they do notdecompose) in the desired temperature range. Of course, the ionicliquids should not react with any constituents of the oxygen generatingcomposition, the acidic compound and the basic compound. The ionicliquids may be used singly or in combinations of two or more. Thus, inexemplary embodiments, this invention uses ionic liquid formulationscontaining one or more ionic liquids and, optionally, contain furtheradditives which do not detrimentally interfere with the peroxidedecomposition reaction.

As an oxygen source, peroxide compounds, in particular solid hydrogenperoxide adduct compounds are used. Solid hydrogen peroxide adductcompounds constitute suitable and stable substituents for liquidhydrogen peroxide, are easily storable, long term stable and safe towork with. Exemplary oxygen sources are alkali percarbonates, e.g.sodium percarbonate (Na₂CO₃×1.5H₂O₂), alkali perborates, e.g. sodiumperborate (NaBO₃×4H₂O, NaBO₃× H₂O), and urea hydrogen peroxide (UHP). InUHP urea and hydrogen peroxide are present in a molar ratio of about1:1.

The peroxide compounds are not particularly limited, as long as they arestable under usual storage conditions. Exemplary peroxide compounds arestable also at elevated temperatures, for example in the vicinity of afire. The peroxide compounds can be soluble or partially soluble orinsoluble in the ionic liquids. The peroxide compounds can be usedsingly or in combinations of two or more, i.e. as oxygen sourceformulations containing, optionally, further additives which do notdetrimentally interfere with the peroxide decomposition reaction.

In exemplary embodiments, the decomposition reaction of the peroxidecompound is catalyzed by metal salts. The metals salts comprise onesingle metal or two or more different metals and an organic and/or aninorganic anion.

In exemplary embodiments the metal salt is soluble in the ionic liquid,and in further exemplary embodiments, the metal salt is not soluble orpartially soluble in the ionic liquid. Selecting a metal salt and anionic liquid such, that the desired amount of metal salt is completelydissolved in the desired amount of ionic liquid provides the advantagethat the metal salt and the ionic liquid can be provided in the form ofone single homogeneous component. The solutions are stable, and evenduring long term storage, no sedimentation takes place. Providing themetal salt and the ionic liquid in the form of a homogeneous solutionsimplifies the design of oxygen generating devices, results in a higheractivity of the mixture of catalyst and ionic liquid and, in turn,reduces the required amount of catalyst. A further advantage is theprolonged shelve life of the compositions, as compared to compositionscontaining the catalyst in suspended form.

The solubility behavior of metal salts in ionic liquids is, at leastroughly, analogous to the solubility behavior in water. Therefore, ifreadily soluble catalysts are desired, metal salts known to be readilysoluble in water can be used, and if hardly soluble catalysts aredesired, metal salts known to be hardly soluble in water can be used.

As regards inorganic anions, anions such as chlorides, sulfates,carbonates, hydroxides, and nitrates are known to provide watersolubility, and as regards organic anions, anions such as chelatingagents, i.e. anions forming coordination complexes with metals, areknown to provide water solubility.

Accordingly, in exemplary embodiments, the metal salt is at least oneselected from the group consisting of chlorides, sulfates, carbonates,hydroxides, and nitrates. Metal salts having these inorganic anions aregenerally well soluble in many ionic liquids.

In further exemplary embodiments, the metal salt is at least oneselected from the group consisting of acetates, acetylacetonates,oxalates, tartrates, and citrates. Metal salts having these chelatingorganic anions are generally well soluble in many ionic liquids.

In further exemplary embodiments, a fraction of the organic or inorganicanions is substituted by oxygen anions, thus yielding mixed catalysts,i.e. metal compounds comprising both oxidic anions and inorganic anionsor organic anions, or even metal compounds comprising oxidic anions,inorganic anions, and organic anions.

The metal salt, in exemplary embodiments, contains one single metal,optionally in different oxidation states, the metal being selected fromthe metals belonging to groups 5 to 14 and periods 4 to 6 of theperiodic table of the elements. The periodic table has 18 groups and 7periods (see: Pure and Applied Chemistry, 1988, Vol. 60, No. 3, pages431-436).

In further exemplary embodiments, the metal salt comprises at least twodifferent metals, with at least one metal being selected from the metalsbelonging to groups 5 to 14 and periods 4 to 6 of the periodic table ofthe elements.

In all embodiments, each metal may be present in one single oxidationstate or in different oxidation states.

The metal salts may be used singly or in combinations of two or moredifferent metal salts. The salts may have different cations or differentanions or both different cations and different anions. The metal saltsmay be provided in the form of metal salt formulations, i.e. thecatalyst may be one single metal salt or a combination of two metalsalts, and optionally additives which do not detrimentally interferewith the peroxide decomposition reaction may also be contained.

The metal salt comprises at least one metal in an oxidation stateallowing a reaction with hydrogen peroxide, assuming basic conditions inaqueous reaction media, i.e. the redox potential of the oxidation statetransition which the metal undergoes during the catalytic reaction mustallow a reaction with hydrogen peroxide.

Exemplary metal salt catalysts include salts of vanadium, chromium,manganese, iron, cobalt, copper, molybdenum, ruthenium, iridium, andlead. Exemplary oxidation states are +2 for vanadium, +3 and +6 forchromium, +2 and +3 for manganese, +2 and +3 for iron, +2 for cobalt, +1and +2 for copper, +6 for molybdenum, +3 for ruthenium, +3 for iridium,and +2 and +4 for lead.

As exemplary inorganic salts catalyzing the peroxide decompositionreaction may be mentioned: PbCl₂, CrCl₃, CoCl₂, CoCO₃, CoSO₄, IrCl₃,MnCl₂, VCl₂, KCr(SO₄)₂, FeCl₃, CuCl₂, and their respective hydrates.

As exemplary organic salts catalyzing the peroxide decompositionreaction may be mentioned: Mn(OAc)₂, Mn(OAc)₃, Mn(acac)₂, Mn(oxalate),Pb(acac)₂, Pb(OAc)₂, Pb₃ (citrate)₂, Pb(tartrate), Co(OAc)₂,MoO₂(acac)₂, Ru(acac)₃. and their respective hydrates. OAc means acetateand acac means acetylacetonate.

The above listed inorganic and organic salts constitute active catalystsin many ionic liquids.

The acidic compounds according to exemplary embodiments are inorganicacids, organic acids, acidic salts, or ionic liquids with acidicproperties.

Examples for inorganic acids are hydrochloric acid, sulfuric acid,nitric acid and phosphoric acid; examples for organic acids are aceticacid, succinic acid, citric acid, and benzoic acid, examples for acidicsalts are sodium hydrogen sulfate and monopotassium phosphate, andexamples for ionic liquids with acidic properties are1-ethyl-3-methylimidazolium hydrogen sulfate ([EMIM][HSO₄]),trimethylammonium propanesulfonic acid hydrogen sulfate ([TMPSA][HSO₄]),1-(4-sulfobutyl)-3-methylimidazolium hydrogen sulfate ([SBMIM][HSO₄])and diethylmethylammonium methanesulfonate ([NEt₂MeH][MeSO₃]).

In the oxygen generators of the present invention, the acidic compounds(“acids”) may be provided in liquid form. Liquid forms include the pureliquid compound, concentrated or diluted solutions of liquids or gases(for example concentrated or diluted solutions of hydrochloric acid oracetic acid), and solutions and dispersions of solid acids or acidicsalts in a solvent or dispersing agent. Acids in liquid form can be,e.g., usual mineral acids such as hydrochloride acid, sulfuric acid,nitric acid and phosphoric acid. Acids in liquid form may also besolutions of acidic salts such as succinic acid, sodium hydrogensulphate, potassium dihydrogen phosphate or crotonic acid. The acid mayalso be a pure liquid compound such as acetic acid or valeric acid.

Exemplary solvents or dispersing agents are water and ionic liquids.Ionic liquids having high viscosity can be used, for example, inadmixture with ionic liquids having lower viscosity.

In exemplary embodiments, the acidic compounds are provided in solidform, for example in the form of a powder, of pellets or beads. Acidiccompounds that may be provided in a solid form are solid acids such assuccinic acid, citric acid or benzoic acid, and acidic salts such sodiumhydrogen sulfate or monopotassium phosphate.

The basic compounds (“bases”) according to exemplary embodiments areprovided in solid form, for example in the form of a powder, of pelletsor of beads. It is also possible that the basic compound is not addedfrom outside to the running oxygen generating reaction but from one ormore tuner compact(s) that are added to the oxygen generatingcomposition before or at the beginning of the reaction. Tuner compactsare pellets comprising the basic compound in solid form and having twoor more layers that are able to release the basic compounds at apredetermined time after start of the oxygen generating reaction suchthat the basic compound is added to the composition for generatingoxygen by release from the tuner compact(s). Optionally, it is alsopossible that the tuner compact comprises at least one layer releasingthe acidic compound at another time than the basic compound, wherein theacidic compound is also present in solid form. In this way it ispossible to release the basic compound and, optionally, the acidiccompound without access to the composition for generating oxygen fromoutside. This allows to adjust oxygen production rate such that noextrema arise. According to further exemplary embodiments the basiccompounds are provided in the form of the pure liquid compounds, or inthe form of concentrated or diluted solutions or dispersions in asolvent or dispersing agent.

Exemplary solvents or dispersing agents are water and ionic liquids.Ionic liquids having high viscosity may be used, for example, inadmixture with ionic liquids having lower viscosity.

Exemplary bases are hydroxides such as potassium hydroxide, sodiumhydroxide and calcium hydroxide, basic salts such as potassiumphosphate, sodium acetate, sodium percarbonate, potassium carbonate,basic oxides such as calcium oxide, and ionic liquids with basicproperties, such as 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]),tetrabutylammonium arginine ([TBA][Arg]), and tetrabutylammoniumbut-3-enoate ([NEt₄][but-3-enoate]).

In the context herein, the term “composition” includes embodimentswherein all constituents of the composition are mixed, i.e., they are incontact with each other, as well as embodiments wherein the constituentsare not in contact with each other, i.e., they are physically separated,or wherein some but not all constituents are in contact with each other.It must be considered that a mixture comprising an ionic liquid, aperoxide compound dissolved or dispersed therein, and a metal salt ascatalyst, is not stable, unless the ionic liquid is an acidic compoundor contains an acidic compound or the ionic liquid is not a basiccompound and does not contain any basic compound. When ionic liquidshaving basic functionality are used, the decomposition of the peroxidecompound starts as soon as the catalyst comes into contact with theperoxide compound, in the ionic liquid, or at least shortly thereafter.Therefore, the constituents of the composition for generating oxygenmust be stored in a condition wherein the catalyst cannot trigger therelease of oxygen from the peroxide compound. This can be achieved byproviding the composition for generating oxygen in the form of a “kit ofparts”, i.e. as a combination of at least two components, the twocomponents comprising the at least one oxygen source, the at least oneionic liquid, and the at least one catalyst compound. In the at leasttwo components, at least one of the three constituents (the oxygensource(s), the ionic liquid(s), and the catalyst is not in contact withthe other constituents of the composition for generating oxygen.

For example, the composition may comprise a first component and a secondcomponent, the first component comprising the oxygen source and thecatalyst, and the second component comprising the ionic liquid or thefirst component comprising the oxygen source and the ionic liquid, andthe second component comprising the catalyst or the first componentcomprising the ionic liquid and the catalyst, and the second componentcomprising the oxygen source.

The situation may be different when the ionic liquid has acidicproperties or when the ionic liquid contains a compound having acidicproperties.

The inventors have found that the peroxide decomposition reaction doesnot proceed or is at least decelerated in an acidic or neutralenvironment. Therefore, in compositions for generating oxygen whichcontain an acidic or neutral ionic liquid, the peroxide, the catalystand the ionic liquid do not need to be stored physically separated, butcan be in contact with each other, e.g. mixed. The inventors havefurther found, that in compositions for generating oxygen comprising anacidic or neutral ionic liquid, the peroxide decomposition reaction canbe started by adding a basic compound to the ionic liquid, the catalystand the peroxide.

Accordingly, an exemplary composition for generating oxygen comprises anoxygen source, a metal salt as a catalyst, an acidic ionic liquid (anionic liquid which is acidic itself, or which is acidic because itcontains an acidic compound) or a neutral ionic liquid and a basiccompound. The oxygen source comprises a peroxide compound, the ionicliquid is in the liquid state at least in a temperature range from −10°C. to +50° C., and the metal salt comprises one single metal or two ormore different metals, and an organic and/or an inorganic anion.

An exemplary oxygen generator comprises the above composition forgenerating oxygen and a further acidic compound for decelerating orstopping the oxygen production.

A further exemplary composition for generating oxygen comprises anoxygen source, a metal salt as a catalyst, and an ionic liquid (aneutral ionic liquid or a basic ionic liquid, i.e. an ionic liquid whichis basic itself or which is basic because it contains a basic compound).The oxygen source comprises a peroxide compound, the ionic liquid is inthe liquid state at least in a temperature range from −10° C. to +50°C., and the metal salt comprises one single metal or two or moredifferent metals, and an organic and/or an inorganic anion.

A further exemplary oxygen generator comprises the above composition forgenerating oxygen and a basic compound for starting or acceleratingoxygen production.

The compositions for generating oxygen may comprise from about 10 to 80weight % of one or more oxygen sources, from about 20 to 80 weight % ofone or more ionic liquids, and from more than 0 up to about 15 weight %of one or more metal salt catalysts. In exemplary embodiments, theoxygen source or mixture of oxygen sources constitutes from 40 to 70weight %, the ionic liquid or mixture of ionic liquids constitutes from30 to 60 weight %, and the catalyst or mixture of catalysts constitutesfrom more than 0 up to about 10 weight % of the composition. In someembodiments, the oxygen source may constitute up to 98 weight % of thecomposition, with the amounts of ionic liquid and catalyst being presentin amounts as low as about 1% by weight, each. Optionally, furtherconstituents may be present, for example silicon dioxide (as a heatsink) and/or radical scavengers, such as resorcinol,2-methylhydrochinone, eugenol, phenol, and 4-propylphenol, all of whichreduce the peroxide decomposition rate. In some embodiments, the amountsof such additional constituents do not exceed about 20 weight % of thecomposition. All constituents together add up to 100 weight %.

In the case of acidic ionic liquids, exemplary compositions alsocomprise a basic compound. The basic compound may be added in an amountwhich is at least sufficient to neutralize the ionic liquid. The amountsof the remaining constituents of the compositions are lessenedproportionally.

An exemplary method for generating oxygen comprises providing an oxygensource, providing a basic ionic liquid, providing a metal salt, andgenerating oxygen by contacting the oxygen source, the ionic liquid andthe metal salt. The oxygen source is a peroxide compound, the ionicliquid is in the liquid state at least in the temperature range from−10° C. to +50° C., and the metal salt comprises one single metal or twoor more different metals, and an organic and/or inorganic anion.

According to an exemplary embodiment, the catalyst and the ionic liquidare provided as a first component, the oxygen source is provided as asecond component, and the step of contacting comprises mixing the firstcomponent and the second component.

According to a further exemplary embodiment, the oxygen source and thecatalyst are provided as a first component, the ionic liquid is providedas a second component, and the step of contacting comprises mixing thefirst component and the second component.

When the oxygen source and the catalyst are provided as one singlecomponent, i.e. in an admixed state, both the oxygen source and thecatalyst should be thoroughly dried before mixing. Otherwise, the oxygensource may be decomposed inadvertently. In the absence of any mediator,for example water or an ionic liquid, the solid oxygen source and thesolid catalyst constitute long-term stable mixtures.

According to a further exemplary embodiment, the oxygen source and theionic liquid are provided as a first component, the catalyst is providedas a second component, and the step of contacting comprises mixing thefirst component and the second component.

A further exemplary method for generating oxygen comprises providing anoxygen source, providing an acidic ionic liquid, providing a metal salt,providing a basic compound, and generating oxygen by contacting theoxygen source, the ionic liquid, the metal salt and the basic compound.The oxygen source is a peroxide compound, the ionic liquid is in theliquid state at least in the temperature range from −10° C. to +50° C.,and the metal salt comprises one single metal or two or more differentmetals, and an organic and/or inorganic anion.

According to an exemplary embodiment, the oxygen source, the catalystand the ionic liquid are provided as a first component, the basiccompound is provided as a second component, and the step of contactingthe oxygen source, the ionic liquid, the catalyst and the basic compoundcomprises mixing the first component and the second component.

According to a further exemplary embodiment, the oxygen source isprovided as a first component, the ionic liquid and the catalyst areprovided as a second component, and the basic compound is provided as athird component, and the step of contacting comprises mixing the firstcomponent, the second component and the third component.

In the above methods for generating oxygen, the oxygen is produced witha particular production rate and for a particular time. The productionrate and time can be influenced to some extent by appropriatelyselecting the type and amounts of the constituents, however, each oxygengenerator having a particular combination of constituents producesoxygen at a rate inherent to that particular combination. There is nopossibility to influence a running decomposition reaction.

The present invention provides the possibility to stop the peroxidedecomposition reaction before the whole amount of oxygen is released.Alternatively, the oxygen production rate may be not stopped, but onlydecreased. Those effects can be achieved by adding an appropriate amountof an acidic compound. Depending on the type and the amount of acid, theoxygen production is stopped or is only decreased to a greater or lesserextent. The interruption or deceleration of the oxygen production may beobserved instantaneously upon addition of the acid to the oxygengenerating composition.

The present invention provides also the possibility to start adecomposition reaction or to restart an interrupted decompositionreaction or to increase the oxygen production rate of a runningdecomposition reaction. These effects can be achieved by adding anappropriate amount of a basic compound to the composition for generatingoxygen. Start or restart of the oxygen production or acceleration of theoxygen production may be observed instantaneously upon addition of thebasic compound to the composition for generating oxygen. After restartof an interrupted decomposition process, the pristine oxygen productionrate may be achieved within a few seconds. Depending on the type andamount of the basic compound the oxygen production can be accelerated toa greater or lesser extent.

An exemplary method for starting or accelerating the oxygen productionof an oxygen generator comprises providing an oxygen source, providingan ionic liquid (acidic or neutral), providing a metal salt, contactingthe oxygen source, the ionic liquid and the metal oxide compound, andstarting or accelerating the oxygen production by adding a basiccompound to the oxygen source, the ionic liquid and/or the metal salt.

A further exemplary method for accelerating or starting the oxygenproduction of an oxygen generator comprises providing an oxygen source,providing an acidic ionic liquid, providing a metal salt, providing abasic compound, generating oxygen by contacting the oxygen source, theionic liquid, the metal salt and the basic compound, and starting oraccelerating the oxygen production by adding a further basic compound tothe oxygen source, the ionic liquid, the metal salt and the basiccompound.

Oxygen production interruption and restart of the oxygen production canbe performed multiple times over the course of the decompositionreaction. Thus, it is possible to adapt the oxygen production rate tothe particular needs. In situations where a user needs more oxygen, hemay increase the oxygen flow rate, and in situations where he needs lessoxygen he may save oxygen by decreasing or even interrupting the oxygenproduction. The inventive method for controlling the oxygen productionrate of an oxygen generator supplies oxygen in a manner similar to aliquid oxygen supply system or a pressurized oxygen tank.

It goes without saying that in the above methods the acidic compound andthe basic compound are not added simultaneously, but rather at therespective time when stop or decrease of oxygen production, or start,restart or increase of oxygen production, respectively, are desired.

The oxygen source, the ionic liquid, the metal salt, the acidic compoundand the basic compound are as described above.

In an exemplary method, the oxygen production is decelerated orinterrupted after a desired time interval by adding an acidic compoundto the oxygen source, the ionic liquid and the catalyst. After a furtherdesired time interval, the oxygen production may be accelerated orrestarted by adding a basic compound or a further basic compound to theoxygen source, the ionic liquid, and the catalyst.

According to further exemplary methods, acceleration and/or decelerationof the oxygen production is performed stepwise by adding severalportions of a basic compound or a further basic compound or an acidiccompound or a further acidic compound, respectively, with time intervalsbetween the individual addition steps.

In another exemplary method, the process of decelerating or interruptingthe oxygen production and the process of accelerating or restarting theoxygen production are performed several times.

Many compositions for generating oxygen do not produce constant oxygenflow rates, but rather show increasing or decreasing oxygen flow rates.In other oxygen generating compositions, oxygen flow rates fluctuateduring the peroxide decomposition reaction. Fluctuating or increasing ordecreasing oxygen flow rates, however, are undesirable. The presentinvention offers a possibility to influence the decomposition reaction,i.e. to accelerate the reaction when the oxygen flow rate decreases, andto decelerate the reaction when the oxygen flow rate increases, thusrendering the oxygen flow rate constant over the course of time.

In the context of this invention, a liquid is regarded neutral if its pHis in a range from 6.5 to 7.3 (because they contain an ionic liquidhaving a pH in this range intrinsically, or because they contain anionic liquid having a pH in a different range, but the pH has beenadjusted by adding an acidic or a basic compound, respectively).

In the context of this invention, a liquid is regarded acidic if its pHis in a range below 6.5. In ionic liquids having a pH below 6.5 (becausethey contain an ionic liquid having a pH below 6.5 intrinsically, orbecause they contain an ionic liquid having a different pH, but the pHhas been adjusted by adding an acidic compound), the peroxidedecomposition reaction proceeds slower than at a pH of 6.5 or above. Thelower the pH value, the slower the decomposition reaction, and anincreasingly higher amount of peroxide compound remains as anundecomposed residue. For the ability to stop oxygen production, thepK_(a)-value of the acidic compound and/or the further acidic compoundhas been found to be important. In an embodiment of the invention thepK_(a)-value of the acidic compound and/or the further acidic compoundis below 5, in particular below 4.5, in particular below 4, inparticular below 3.5, in particular below 3, in particular below 2.5, inparticular below 2, in particular below 1.5, in particular below 1, inparticular below 0.5, in particular below 0. The pK_(a)-values arealways given for 25° C. as standard condition. The pK_(a)-value is anintrinsic feature of the acidic compound and/or the further acidiccompound. Usually, pK_(a)-values of known acidic compounds or knownfurther acidic compounds are known in the art. The pK_(a)-values can bedetermined by methods well-known in the art, e.g. by means of titration.

The acidic compound and/or the further acidic compound and the amount ofacidic compound and/or the further acidic compound where the peroxidedecomposition does not proceed at all, depends on the types of ionicliquid, peroxide and catalyst, and can be easily found for eachparticular system by a few routine experiments.

In the context of this invention, a liquid is considered basic if its pHis in a range above 7.3. In ionic liquids having a pH above 7.3 (becausethey contain an ionic liquid having a pH above 7.3 intrinsically, orbecause they contain an ionic liquid having a different pH, but the pHhas been adjusted by adding a basic compound), the peroxidedecomposition reaction proceeds faster than at a pH of 7.3 or below. Thehigher the pH value, the faster the peroxide is decomposed, i.e. theshorter the time period needed for complete decomposition of theperoxide. Again, reaction speeds somewhat vary depending on the types ofionic liquid, peroxide and decomposition catalyst, but a desiredreaction speed for a particular system can be easily found by a fewroutine experiments. For the ability to start oxygen production, thepK_(b)-value of the basic compound has been found to be important. In anembodiment of the invention the pK_(b)-value of the basic compoundand/or the further basic compound is below 10, in particular below 9.5,in particular below 9, in particular below 8.5, in particular below 8,in particular below 7.5, in particular below 7, in particular below 6.5,in particular below 6, in particular below 5.5, in particular below 5.The pK_(b)-values are always given for 25° C. as standard condition. ThepK_(b)-value is an intrinsic feature of the basic compound and/or thefurther basic compound. Usually, pK_(b)-values of known basic compoundsor known further basic compounds are known in the art. The pK_(b)-valuescan be determined by methods well-known in the art, e.g. by means oftitration.

In an embodiment of the method of the invention the amount of the basiccompound and/or the further basic compound comprised by the oxygengenerator is sufficient for allowing complete oxidation of the metal ionof the metal salt by at least one oxidation state, in particular by twooxidation states. Such an oxidation may be caused by the peroxide asoxidizing agent.

In an embodiment, the oxygen generator according to the inventioncomprises an amount of the basic compound sufficient for allowingcomplete oxidation of the metal ion of the metal salt by at least oneoxidation state, in particular by two oxidation states. This amount canbe easily calculated or experimentally determined. For example, if thebasic compound is NaOH and the metal salt is MnCl₂ the metal iscompletely oxidized when the solution or suspension obtained brown colorof MnO₂ which color does not further increase in intensity.

Herein, the pH value of an ionic liquid is determined in an 100 mMaqueous solution (distilled water) of the ionic liquid at 20° C. The pHvalue can be adjusted as desired by adding acids or bases, respectively,e.g. 1 M HCl or 1 M NaOH.

An exemplary device for generating oxygen in a controlled manner isspecifically adapted for housing the components of the composition forgenerating oxygen in a physically separated state, and for bringing theminto physical contact once generation of oxygen is desired, and forhousing at least one acidic compound and, optionally, at least one basiccompound in such a manner that the acidic compound and the basiccompound can be added to the composition when desired.

In an exemplary embodiment, a device for generating oxygen comprises areaction chamber housing a composition for generating oxygen, thecomposition comprising a combination of constituents consisting of anoxygen source, an acidic ionic liquid and a metal salt, means forallowing oxygen to exit the reaction chamber, and a dosing devicehousing a basic compound, the dosing device being adapted to introducethe basic compound into the reaction chamber.

In another exemplary embodiment, a device for generating oxygen in acontrolled manner comprises a reaction chamber housing a composition forgenerating oxygen, the composition comprising a combination ofconstituents consisting of an oxygen source, an acidic ionic liquid, anda metal salt, means for allowing oxygen to exit the reaction chamber, atleast one dosing device housing a basic compound and at least one dosingdevice housing in acidic compound, the dosing devices being adapted tointroduce the basic compound and the acidic compound into the reactionchamber.

In a further exemplary embodiment, a device for generating oxygen in acontrolled manner comprises a reaction chamber housing a composition forgenerating oxygen, the composition comprising a combination ofconstituents consisting of an oxygen source, a neutral or basic ionicliquid, and a metal salt, at least one dosing device housing an acidiccompound and at least one dosing device housing a basic compound, thedosing device(s) being adapted to introduce the basic compound andoptionally the acidic compound into the reaction chamber, means formaintaining at least one of the oxygen source, the ionic liquid and themetal salt physically separated from the remaining constituents, meansfor establishing physical contact of the oxygen source, the ionic liquidand the metal salt, and means for allowing oxygen to exit the reactionchamber.

The oxygen source, the ionic liquid, the metal salt, the acidic compoundand the basic compound are as described above.

Devices for housing the components of the composition for generatingoxygen in a physically separated state and for bringing them intophysical contact once generation of oxygen is desired, are described inEP 3 323 782 A1, in particular in paragraphs [0053] to [0057] and [0106]to [0127], and are illustrated in FIGS. 18 to 22 of EP 3 323 782 A1. Theentire document and the specific disclosure is incorporated herein byreference.

A device for generating oxygen according to the present invention may bedesigned, for example, as illustrated in FIGS. 19 and 20 of EP 3 323 782A1, however, in the device of present invention, reaction chamber 2 orcompartment 4, respectively, would be filled with an oxygen source, andacidic ionic liquid, and a metal salt, and injection device 21, orcompartment 3, respectively, would be filled with a basic compound.

In order to be suitable as a device for generating oxygen in acontrolled manner according to the present invention, the devicesdisclosed in EP 3 323 782 A1 must be modified by including dosingdevices for housing basic compounds and optionally (further) acidiccompounds, the dosing devices being adapted to introduce the basiccompounds and optionally the acidic compounds into the reaction chamber.Exemplary devices are described with reference to FIGS. 11 and 12 below.

In exemplary embodiments the ionic liquids described above are used asdispersants or solvents and as heat sinks in the oxygen generatordescribed above.

The disclosed generators, methods and devices may take advantage of anyof the materials describe above in relation to compositions and viceversa.

All references herein to “comprising” should be understood to encompass“including” and “containing” as well as “consisting of” and “consistingessentially of”.

The term “a” means “at least one.”

The term “oxygen,” as a product, primarily pertains to oxygen gas in aconcentration and amount that is useful and sufficient for humanbreathing. Oxygen is also produced by the novel process and device fortechnical and other industrial purposes.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIGS. 1-6 are graphs illustrating start of decomposition of UHP (ureahydrogen peroxide) by addition of basic compounds which decomposition iscatalyzed by dissolved metal salts as catalysts,

FIG. 7 is a graph summarizing data deducted from the results given inFIGS. 1 to 6 showing the amount of basic composition required forstarting reaction in dependence from strength of the basic compound,

FIG. 8 is a graph summarizing data deducted from further experiments fordetermination of the amount of basic composition required for startingreaction in dependence from strength of the basic compound,

FIGS. 9 and 10 are graphs illustrating acceleration of decomposition ofUHP, which decomposition is catalyzed by dissolved metal salts andstarted by addition of a basic compound and which acceleration is causedby further basic compound,

FIG. 11 is a sectional view of an embodiment of a device for generatingoxygen according to this invention, and

FIG. 12 is a sectional view of another embodiment of a device forgenerating oxygen according to this invention.

DETAILED DESCRIPTION OF THE INVENTION

In all graphs illustrating oxygen release, oxygen flow rate and volumeare plotted against runtime, wherein runtime is the time which startsrunning at the time point of contacting the oxygen source, the ionicliquid, the metal salt with a basic compound. “Volume” is the oxygenvolume released in total. Oxygen flow rate (I/h) and volume released (I)by each decomposition reaction where measured with a drum gas meter ineach of the experiments of examples 1 to 3, throughout the experiments.

Example 1

In example 1 different basic compounds were added to oxygen generatingcompositions comprising ionic liquid, a Mn²⁺-salt and UHP for evaluatingconditions required for starting oxygen generation. In general, 100 gurea hydrogen peroxide (UHP) were mixed with 1 mol % MnCl₂ with respectto the amount of UHP which MnCl₂ was dissolved in 30 g of an ionicliquid which was [EMIM][EtSO₄] or [MMIM][PO₄Me₂]. The resulting mixturegenerated no oxygen. After 10 minutes given for equilibration a solutionof a basic compound in 10 g [EMIM][EtSO₄] or [MMIM][PO₄Me₂] was added tothe mixture. The kind of basic compound and the amount of basic compoundwere varied in these experiments. Volume of the oxygen produced in thereactions was measured by means of the gas meter.

Since the oxygen generating mixture needed some time for starting insome cases released volume of oxygen was only assessed 50 minutes afteraddition of the basic compound. The reaction was considered as startedwhen more than 0.5 g UHP were degraded after 50 minutes. The amountrequired for starting the reaction was determined from the experimentaldata by linear approximation.

In experiments 1 to 17 the types and amounts of compounds given in belowtables have been used.

TABLE 1 Catalyst Peroxide IL Base n(Base)/ n(Base)/ Experiment (Mass)(Mass) (Mass) (Mass) n(IL) n(MnCl₂) 1 MnCl₂ UHP [MMIM][PO₄Me₂] TRIS(325.0 mg) in 10 g 0.0149 0.252 (1.34 g) (100 g) (30 g) [MMIM][PO₄Me₂] 2MnCl₂ UHP [EMIM][EtSO₄] TRIS (81.3 mg) in 10 g 0.00390 0.0630 (1.34 g)(100 g) (30 g) [MMIM][PO₄Me₂] 3 MnCl₂ UHP [MMIM][PO₄Me₂] TRIS (40.6 mg)in 10 g 0.00190 0.0315 (1.34 g) (100 g) (30 g) [MMIM][PO₄Me₂]Results are given in FIG. 1.

TABLE 2 Catalyst Peroxide IL Base n(Base)/ n(Base)/n Experiment (Mass)(Mass) (Mass) (Mass) n(IL) (MnCl₂) 4 MnCl₂ UHP [EMIM][EtSO₄] Imidazole(340 mg) in 10 g 0.0295 0.469 (1.34 g) (100 g) (30 g) [EMIM][EtSO₄] 5MnCl₂ UHP [EMIM][EtSO₄] Imidazole (170 mg) in 10 g 0.0148 0.234 (1.34 g)(100 g) (30 g) [EMIM][EtSO₄] 6 MnCl₂ UHP [EMIM][EtSO₄] Imidazole (85 mg)in 10 g 0.00738 0.117 (1.34 g) (100 g) (30 g) [EMIM][EtSO₄]Results are given in FIG. 2.

TABLE 3 Catalyst Peroxide IL Base n(Base)/ n(Base)/n Experiment (Mass)(Mass) (Mass) (Mass) n(IL) (MnCl₂) 7 MnCl₂ UHP [EMIM][EtSO₄]2-Methylpyridine (3 g) 0.190 3.02 (1.34 g) (100 g) (30 g) in 10 g[EMIM][EtSO₄] 8 MnCl₂ UHP [EMIM][EtSO₄] 2-Methylpyridine (0.6 g) 0.03810.605 (1.34 g) (100 g) (30 g) in 10 g [EMIM][EtSO₄] 9 MnCl₂ UHP[EMIM][EtSO₄] 2-Methylpyridine (0.3 g) 0.0190 0.302 (1.34 g) (100 g) (30g) in 10 g [EMIM][EtSO₄] 10 MnCl₂ UHP [EMIM][EtSO₄] 2-Methylpyridine(0.1 g) 0.00634 0.101 (1.34 g) (100 g) (30 g) in 10 g [EMIM][EtSO₄]Results are given in FIG. 3.

TABLE 4 Catalyst Peroxide IL Base n(Base)/ n(Base)/n Experiment (Mass)(Mass) (Mass) (Mass) n(IL) (MnCl₂) 11 MnCl₂ UHP [EMIM][EtSO₄]p-Toluidine (4 g) in 10 g 0.221 3.51 (1.34 g) (100 g) (30 g)[EMIM][EtSO₄] 12 MnCl₂ UHP [EMIM][EtSO₄] p-Toluidine (2 g) in 10 g 0.1101.75 (1.34 g) (100 g) (30 g) [EMIM][EtSO₄] 13 MnCl₂ UHP [EMIM][EtSO₄]p-Toluidine (1 g) in 10 g 0.0551 0.876 (1.34 g) (100 g) (30 g)[EMIM][EtSO₄]Results are given in FIG. 4.

TABLE 5 Catalyst Peroxide IL Base n(Base)/ n(Base)/n Experiment (Mass)(Mass) (Mass) (Mass) n(IL) (MnCl₂) 14 MnCl₂ UHP [EMIM][EtSO₄] Aniline (5g) in 10 g 0.317 5.04 (1.34 g) (100 g) (30 g) [EMIM][EtSO₄] 15 MnCl₂ UHP[EMIM][EtSO₄] Aniline (2 g) in 10 g 0.127 2.02 (1.34 g) (100 g) (30 g)[EMIM][EtSO₄]Results are given in FIG. 5.

TABLE 6 Catalyst Peroxide IL Base n(Base)/n n(Base)/n Experiment (Mass)(Mass) (Mass) (Mass) (IL) (MnCl₂) 16 MnCl₂ UHP [EMIM][EtSO₄]2,6-Dimethylaniline (8 g) 0.390 6.20 (1.34 g) (100 g) (30 g) in 10 g[EMIM][EtSO₄] 17 MnCl₂ UHP [EMIM][EtSO₄] 2,6-Dimethylaniline (5 g) 0.2443.87 (1.34 g) (100 g) (30 g) in 10 g [EMIM][EtSO₄]Results are given in FIG. 6.

From the results of experiments 1 to 17 a relation between the strengthof the added basic compound and the amount required for starting oxygenproduction by peroxide decomposition according to the above definitioncan be seen. The stronger the basic compound, e.g. the lower thepK_(b)-value, the smaller is the amount of the basic compositionrequired for starting the reaction. Basic compounds having apK_(b)-value above 10 are only able to accelerate oxygen production butnot to start oxygen production. The results are summarized in FIG. 7 andbelow Table 7.

TABLE 7 pK_(b)- n(Base) n(Base)/ n(Base)/ Base Value [mmol] n(IL)n(MnCl₂) TRIS 5.94 0.250 1.38E−3 0.0233 Imidazole 6.95 2.07 12.6E−30.194 2-Methylpyridine 8.06 1.51 9.25E−3 0.147 p-Toluidine 8.92 15.80.0932 1.48 Aniline 9.13 19.4 0.115 1.83 2,6-Dimethylaniline 10.05 66.00.390 6.20 Dimethylphosphate 12.71 180 1.00 16.9

FIG. 7 shows as a function of the strength of the basic compound howmany equivalents of the basic compound in relation to MnCl₂ are requiredfor starting peroxide decomposition. Filled squares symbolize start ofperoxide decomposition by addition of the given amount of basiccompound. Crosses indicate that the amount of the added basic compounddid not result in a start of the reaction. The dotted curve is acalculated curve fitted to the calculated values.

Example 2

In example 2 another approach for determining the influence of thestrength of a basic compound on peroxide decomposition has been used. Ingeneral, 20 g UHP were given in a flask. In 10 g of ionic liquid[MMIM][PO₄Me₂] 1 mol % MnCl₂ with respect to the amount UHP and adefined amount of a basic compound were dissolved. This solution wasthen given into the flask containing the UHP. Kind and amount of thebasic compound dissolved in the ionic liquid were varied. 3 days afterstart of reaction a sodium hydroxide solution was added to the reactionmixture. If not-degraded peroxide was still present in the flask it wasthen degraded. The volume of produced oxygen was measured by means ofthe gas meter. The reaction was considered as started if no peroxidecould be detected in the flask 3 days after start of the reaction. Theamount of basic compound required for start of the reaction has beendetermined from experimental data by linear approximation.

FIG. 8 shows the amount of basic compound required for start of thereaction according to the above definition in dependence from thestrength of the basic compound. Filled circles symbolize the amount ofbasic compound in relation to the amount of ionic liquid sufficient forstart of the oxygen generation. The empty circle refers to a start ofperoxide decomposition, wherein the amount of basic compound is givenfor the first pK_(b)-value of the dibasic disodium malonate.

The results show the relation between the pK_(b)-value of the basiccompound and the amount of this basic compound required for start of thereaction. The results confirm the results obtained with experiment 1.

Example 3

For determining the effect of addition of a basic compound to a runningoxygen production 2 g Sodium acetate and 1.57 g Mn(OAc)₂*4H₂O weredissolved in 30 g of ionic liquid [MMIM][PO₄Me₂] and given to 100 g UHPin a flask. This resulted in peroxide decomposition and release ofoxygen within a short time. Oxygen production rate rose up to 25 I/h andthen decreased continuously. 16:30 minutes after start of the reaction asolution containing 16.5 mmol of a basic compound in 10 g of ionicliquid [MMIM][PO₄Me₂] were added. Type and amount of the differentcompounds of the compositions are given in below table 8.

TABLE 8 Catalyst Peroxide 1^(st) Base 2^(nd) Base strength of BaseExperiment (Mass) (Mass) (Mass) (Mass) (pK_(b)) 18 Mn(OAc)₂*4 UHP[MMIM][PO₄Me₂] TRIS (2.00 g) 5.94 H₂O (100 g) (30 g) + in 10 g (1.57 g)Sodium acetate (2 g) [MMIM][PO₄Me₂] 19 Mn(OAc)₂*4 UHP [MMIM][PO₄Me₂]Imidazole (1.12 g) 6.95 H₂O (100 g) (30 g) + in 10 g (1.57 g) Sodiumacetate (2 g) [MMIM][PO₄Me₂] 20 Mn(OAc)₂*4 UHP [MMIM][PO₄Me₂] Pyridine(1.30 g) 8.94 H₂O (100 g) (30 g) + in 10 g (1.57 g) Sodium acetate (2 g)[MMIM][PO₄Me₂] 21 Mn(OAc)₂*4 UHP [MMIM][PO₄Me₂] Sodium acetate 9.25 H₂O(100 g) (30 g) + (1.35 g) (1.57 g) Sodium acetate (2 g) in 10 g[MMIM][PO₄Me₂]

The volume of oxygen produced is shown in FIG. 9 and the flow rate isshown in FIG. 10. The data show that basic compounds having a biggerstrength of base, i.e. a smaller pK_(b)-value, result in a biggeracceleration of peroxide decomposition.

FIG. 11 illustrates an exemplary device 1 for generating oxygen in acontrolled manner, the device having one single reaction chamber 2 forstoring the composition for generating oxygen. In such a single reactionchamber 2 at least one of the constituents of the composition forgenerating oxygen can be enclosed in a receptacle in order to avoidcontact with the remaining constituents of the composition contained inthe reaction chamber 2. The device is particularly suitable for use withneutral and basic ionic liquids. In the embodiment shown in FIG. 11, tworeceptacles 5, 6 are arranged in the reaction chamber. Receptacle 5contains an intimate mixture of the oxygen source 7 and thedecomposition catalyst 9, for example in powder form or compressed intopellets, in a thoroughly dried condition. Receptacle 6 contains theionic liquid 8. Alternatively, there may be only one receptacle forenclosing the peroxide/catalyst mixture, while the ionic liquid is“free” within reaction chamber 2, or ionic liquid 8 may be enclosedwithin a receptacle, while the peroxide/catalyst mixture is not enclosedin a separate receptacle. Further alternatively, the catalyst may bedissolved (soluble metal salts) or partly dissolved (partly solublemetal salts) or dispersed (insoluble metals salts or metal oxidecompounds) in the ionic liquid. This alternative is particularlyadvantageous. It is, in principle, also possible to enclose only thecatalyst within a separate receptacle, while the ionic liquid and theperoxide are not enclosed. It is only necessary to avoid contact betweenall three constituents during storage of the device for generatingoxygen.

It is desirable to store the peroxide 7, the ionic liquid 8 and thecatalyst 9 within the reaction chamber 2 in such an arrangement that allconstituents will be able to get intimately mixed once oxygen generationis required. When, for example, an insoluble or only partly solublemetal salt is used as a catalyst, and this catalyst and the ionic liquidare provided in one receptacle, and the peroxide in another receptacle,the catalyst may settle within the ionic liquid during storage. In sucha case proper mixing with the peroxide may be inhibited. Quick andperfect mixing of all constituents can be achieved when the peroxide andthe soluble or insoluble catalyst are intimately mixed in advance in adry condition, optionally compacted into molds, and filled either intothe reaction chamber 2 or into a separate receptacle 5 to be placedwithin the reaction chamber 2, and the ionic liquid is provided in aseparate receptacle 6. Quick and perfect mixing can also be achievedwhen the catalyst is soluble in the ionic liquid, and is essentiallydissolved therein. Placing the ionic liquid (or the ionic liquid and thecatalyst) in a separate receptacle, although this is not absolutelynecessary in a case where peroxide and catalyst (or the peroxide alone)are placed in a receptacle 5, constitutes an advantageous precautionarymeasure against accidental mixing of the constituents in case ofreceptacle 5 leakage or breakage. Care must be taken, when UHP andcatalyst are mixed, because UHP is highly hygroscopic.

In a situation where oxygen shall be generated, receptacle 5, orreceptacles 5 and 6, respectively, are destroyed by a breaking device18. In FIG. 11, breaking device 18 has the form of a plate, however,means for destroying the receptacle(s) are not limited to plates, andother means are known to persons skilled in the art, for example firingpins or grids. Movement of plate 18 can be achieved by a spring 19 oranother activation mechanism. During storage of the device forgenerating oxygen, spring 19 is under tension and holds plate 18 at aposition distant from receptacles 5, 6. Once the tension is released bya suitable trigger mechanism (not shown), spring 19 moves plate 18towards receptacles 5, 6, and plate 18 destroys receptacles 5, 6. Such atrigger may be, for example, pulling an oxygen mask towards a passengerin an airplane. Another exemplary trigger mechanism is an oxygen sensorsensing a low oxygen condition.

Receptacles 5, 6, and plate 18 are made from materials which guaranteethat receptacles 5, 6 will be broken or ruptured when hit by plate 18.Exemplary materials are plastic foils or glass for receptacles 5, 6, andthicker plastic material or metal for plate 18.

Destruction of receptacles 5, 6 causes mixing of peroxide, ionic liquid,and catalyst, and initiates oxygen generation. In order to allow thatthe oxygen exits reaction chamber 2, reaction chamber 2 has an opening.In the illustrated embodiment, the opening is sealed with a gaspermeable membrane 16. The opening may be at a different position thanshown in FIG. 11, or there may be more than one opening.

In exemplary embodiments, the oxygen generated in the device describedherein may be passed through a filter or other purification means asknown in the art. The device may be equipped with such means.

The oxygen generating reaction is an only slightly exothermic process,and proceeds at low temperature, i.e. below 150° C., or even below 120°C. or below 100° C. Therefore, reaction chamber 2 does not need toresist high temperatures, and may be made from lightweight, low meltingmaterials such as plastics. In addition, any bulky insulation is notrequired. This is particularly advantageous in all cases where weightmust be saved and/or space is limited, for example in the case of oxygenmasks which shall be installed in an aircraft.

The exemplary device illustrated in FIG. 11 is equipped with twoinjection devices 11, 11′, for examples syringes or other dosingdevices. Openings 17, 17′ fluidly connect the interior spaces ofreaction chamber 2 and of injection devices 11, 11′ respectively.

The injection device 11 comprises a receptacle 12, a slide bar 13 and aspike 14. The injection device 11′ comprises a receptacle 12′, a slidebar 13′ and a spike 14′. Spikes 14, 14′ are held in place by fixtures15, 15′. Receptacles 12, 12′ are made from a material which can easilybe ruptured, for example bags made from plastic foils. Receptacle 12contains an acidic compound and receptacle 12′ contains a basiccompound.

In the exemplary embodiment illustrated in FIG. 11, slide bars 13, 13′can be actuated in an analogous manner as the braking device 18. Onceactuated, slide bar 13 pushes receptacle 12 towards spike 14, receptacle12 is ruptured and acid is injected through opening 17 into reactionchamber 2. Similarly, once actuated, slide bar 13′ pushes receptacle 12′towards spike 14′, receptacle 12′ is ruptured and base is injectedthrough opening 17′ into reaction chamber 2.

Actuation of braking device 18 starts the peroxide decompositionreaction in reaction chamber 2. Without interference, the decompositionreaction proceeds until all peroxide compound has been decomposed. Thedevice illustrated in FIG. 11 allows a user to stop the peroxidedecomposition reaction by actuating slide bar 13, and to save theperoxide not yet decomposed for later use. Whenever oxygen is neededagain, the user may actuate slide bar 13′, thus starting the peroxidedecomposition reaction again.

The device illustrated in FIG. 11 has only one injection device 11containing an acidic compound, and one injection device 11′ containing abasic compound. Such a device allows to stop and to restart the peroxidecomposition reaction only once. Providing reaction chamber 2 withseveral injection devices containing an acid, and with several injectiondevices containing a base allows to stop and to restart the peroxidedecomposition several times. For example, a device 1 for generatingoxygen having three injection devices containing acidic compounds andhaving three injection devices containing basic compounds, allows a userto interrupt and to restart the oxygen production three times, or atleast until all of the oxygen source has been decomposed.

If desired, a device as illustrated in FIG. 11 can be also used forreducing or increasing the oxygen flow rate by injecting an acidiccompound or a basic compound, respectively into reaction chamber 2, forexample when leveling out increasing or decreasing or fluctuating oxygenflow rates shall be achieved.

It is also possible to provide only injection devices filled with acid,or only injection devices filled with base. In such a case, oxygengenerating device 1 will only allow to reduce the oxygen flow rate, orto increase the oxygen flow rate, respectively.

An alternative exemplary device for generating oxygen in a controlledmanner is illustrated in FIG. 12. In FIG. 12 the same reference numeralsas in FIG. 11 are used for designating components which correspond tocomponents already illustrated in FIG. 11.

The device illustrated in FIG. 12 is suitable for use with acidic ionicliquids. In the illustrated embodiment, reaction chamber 2 contains amixture of acidic ionic liquid 8, oxygen source 7 and decompositioncatalyst 9, for example pellets comprising a peroxide/catalyst mixturedispersed within the ionic liquid. Of course, the acidic ionic liquid,the oxygen source and the catalyst may be provided in any differentmanner, for example in the form of a dispersion of oxygen source powderin a solution of the catalyst within the ionic liquid.

The exemplary device illustrated in FIG. 12 is equipped with twoinjection devices 11, 11′, which are identical to the injection devices11, 11′ of the device illustrated in FIG. 11. Injection device 11contains an acidic compound, and injection device 11′ contains a basiccompound. Injection device 11 may be omitted. An oxygen generatingdevice 1 having only injection device 11′ allows to start the peroxidedecomposition reaction by destroying receptacle 12′ and injecting thebasic compound through opening 17′ into reaction chamber 2. The peroxidedecomposition reaction will then proceed until all peroxide compound hasbeen decomposed, and the oxygen generated by the composition reactionwill leave reaction chamber 2 through gas permeable membrane 16.

A device for generating oxygen in a controlled manner needs at least onefurther injection device, for example injection device 11 containing anacidic compound, as illustrated in FIG. 12. Injecting the acidiccompound contained in injection device 11 into reaction chamber 2 allowsto decelerate the peroxide decomposition reaction and to reduce a toohigh oxygen flow rate.

In alternative embodiments, the oxygen generating device illustrated inFIG. 12 may be provided with one or more additional injection devicescontaining basic compounds and/or with one or more additional injectiondevices containing acidic compounds. Such additional injection devicesallow to increase or decrease the oxygen production rate, respectively,or to stop and restart the oxygen production several times.

The oxygen produced according to this invention is pure and at a lowtemperature and, therefore, ideal for applications in airplanes, inself-rescuers and in rebreathers. However, the use for technicalpurposes such as in portable welding devices in mining and submarineapplications, and in spaceflight, e.g. in control nozzles is alsocontemplated.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. An oxygen generator, comprising: a composition for generating oxygenincluding an oxygen source, an ionic liquid, and a metal salt, and abasic compound for starting or accelerating oxygen production; saidoxygen source comprising a peroxide compound; said ionic liquid being inthe liquid state at least in a temperature range from −10° C. to +50°C.; and said metal salt having one single metal or two or more differentmetals, and an organic and/or an inorganic anion.
 2. The oxygengenerator according to claim 1, wherein said oxygen source is selectedfrom the group consisting of alkali metal percarbonates, alkali metalperborates, urea hydrogen peroxide, and mixtures thereof.
 3. The oxygengenerator according to claim 1, wherein said ionic liquid is at leastone salt having a cation and an anion, the cation is selected from thegroup consisting of imidazolium, pyrrolidinium, ammonium, pyridinium,pyrazolium, piperidinium, phosphonium, and sulfonium cations, and/or theanion is selected from the group consisting of dimethylphosphate,methylsulfate, ethylsulfate, trifluoromethylsulfonate,bis(trifluoromethylsulfonyl)imide, chloride, bromide, iodide,tetrafluoroborate, hexafluorophosphate, acetate, and but-3-enoate. 4.The oxygen generator according to claim 1, wherein said metal saltcomprises at least one cation selected from the group consisting ofvanadium, chromium, manganese, iron, cobalt, copper, molybdenum,ruthenium, iridium, and lead.
 5. The oxygen generator according to claim1, further comprising an acidic compound for decelerating or stoppingoxygen production.
 6. The oxygen generator according to claim 5, whereinsaid acidic compound is selected from the group consisting of inorganicacids, organic acids, acidic salts and ionic liquids having acidicfunctionality.
 7. The oxygen generator according to claim 6, whereinsaid acidic compound is selected from the group consisting ofhydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, aceticacid, succinic acid, citric acid, benzoic acid, sodium hydrogen sulfate,monopotassium phosphate, 1-ethyl-3-methylimidazolium hydrogen sulfate,trimethylammonium propane-sulfonic acid hydrogen sulfate,1-(4-sulfobutyl)-3-methylimidazolium hydrogen sulfate, anddiethylmethylammonium methanesulfonate.
 8. The oxygen generatoraccording to claim 1, wherein said basic compound is selected from thegroup consisting of hydroxides, basic oxides, basic salts and ionicliquids having basic properties.
 9. The oxygen generator according toclaim 1, wherein said basic compound is selected from the groupconsisting of sodium hydroxide, potassium hydroxide, potassiumphosphate, sodium acetate, sodium percarbonate, potassium carbonate,calcium hydroxide, calcium oxide, 1-ethyl-3-methylimidazolium acetate,tetrabutylammonium arginine, and tetraethylammonium but-3-enoate. 10.The oxygen generator according to claim 1, wherein a pK_(b)-value ofsaid basic compound is below 10, and/or wherein the oxygen generatorfurther comprises an amount of said basic compound sufficient forallowing complete oxidation of said metal ion of said metal salt by atleast one oxidation state.
 11. The oxygen generator according to claim10, wherein the pK_(b)-value of said basic compound is below 9.5 andsaid basic compound is present in an amount sufficient for allowing thecomplete oxidation of said metal ion by two oxidation states.
 12. Theoxygen generator according to claim 5, wherein said acidic compound isprovided in solid form or in a solution or dispersion or as a pureliquid substance, and/or wherein said basic compound is provided insolid form or in a solution or dispersion or as a pure liquid substance.13. The oxygen generator according to claim 12, wherein said acidiccompound is a tuner compact.
 14. A composition for generating oxygen,comprising: an oxygen source, an ionic liquid, a metal salt, and a basiccompound; or if the ionic liquid is a basic ionic liquid or the oxygensource is basic, an oxygen source, an ionic liquid and a metal salt;wherein: the oxygen source comprises a peroxide compound; the ionicliquid is in a liquid state in a temperature range from −10° C. to +50°C.; and the metal salt comprises one single metal or two or moredifferent metals, and an organic and/or an inorganic anion.
 15. A methodof starting or accelerating an oxygen production of an oxygen generatingcomposition, the method comprising: providing an oxygen sourcecomprising a peroxide compound; providing an ionic liquid, which in aliquid state in a temperature range from −10° C. to +50° C.; providing ametal salt, the metal salt having one single metal or two or moredifferent metals, and an organic and/or an inorganic anion; contactingthe oxygen source, the ionic liquid and the metal salt; and starting oraccelerating the oxygen production by adding a basic compound to theoxygen source, the ionic liquid, and/or the metal salt.
 16. The methodaccording to claim 15, which comprises decelerating or stopping theoxygen production after a desired time interval by adding an acidiccompound, once or multiple times.
 17. The method according to claim 15,wherein a pK_(b)-value of the basic compound and/or a further basiccompound is below
 10. 18. The method according to claim 15, whichcomprises setting an amount of the basic compound to be sufficient forallowing complete oxidation of the metal ion of the metal salt by atleast one oxidation state.
 19. The method according to claim 18, whereina pK_(b)-value of the basic compound and/or a further basic compound isbelow 9.5 and an amount of the basic compound is sufficient tocompletely oxidize the metal ion of the metal salt by at least twooxidation states.
 20. A device for generating oxygen in a controlledmanner, the device comprising: a reaction chamber for housing acomposition for generating oxygen, the composition being a combinationof constituents including of an oxygen source, an ionic liquid, and ametal salt; at least one dosing device housing a basic compound andbeing configured for introducing the basic compound into said reactionchamber, and, optionally, at least one dosing device housing an acidiccompound and being configured for introducing the acidic compound intosaid reaction chamber; a separator device for maintaining at least oneof the oxygen source, the ionic liquid, and the metal salt physicallyseparated from remaining constituents of the composition for generatingoxygen; a device for establishing physical contact between the oxygensource, the ionic liquid, and the metal salt; and a device for allowingoxygen to exit the reaction chamber; or a reaction chamber housing acomposition for generating oxygen, the composition comprising acombination of constituents including of an oxygen source, an ionicliquid, and a metal salt; a device for allowing oxygen to exit thereaction chamber; at least one dosing device housing a basic compoundand being configured for introducing the basic compound into saidreaction chamber, and, optionally, at least one dosing device housing anacidic compound and being configured for introducing the acidic compoundinto said reaction chamber; wherein: the metal salt comprises a singlemetal or two or more different metals, and an organic and/or aninorganic anion; the oxygen source comprises a peroxide compound, theionic liquid is in the liquid state at least in the temperature rangefrom −10° C. to +50° C.; and a control device for controlling an oxygenproduction rate by selectively adding the basic compound or, optionally,the acidic compound to the composition for generating oxygen.